Changes in Gd₂O₃ films grown on Si(100) as a function of nitridation temperature and Zr incorporation

We investigated Gd₂O₃ and Zr-incorporated Gd₂O₃ films grown on Si (100) as a function of nitridation temperature under an NH₃ ambient and the incorporation of Zr into the film. The formation of a silicide layer at the interfacial region was suppressed in cases of Zr-incorporated or NH₃-nitried Gd₂O₃ films. The crystalline structure was affected when zirconium, with a relatively small ionic radius, was substituted with gadolinium. When the concentration of Zr atoms in a Gd₂O₃ film reaches a specific level (Gd_0.6Zr_1.9O_4.3), phase transition occurred from cubic Gd₂O₃ to monoclinic ZrO₂. However, the monoclinic phase disappeared after nitridation at 900 °C in an NH₃ ambient. The majority of the nitrogen atoms accumulated near the interface in the films and the concentration of incorporated N increased with increasing Zr content and NH₃ annealing temperature. Moreover, nitrogen atoms bonded to Zr-silicate at the interface, in preference to ZrO₂ in the film. These incorporation characteristics of nitrogen into Zr-incorporated Gd₂O₃ film have an effect on the thermal stability and crystalline structure of a film.